Download JNTUA (JNTU Anantapur) M.Tech ( Master of Technology) 2nd Semester Supply 2018 Feb 9D15203 Mechanical Vibrations Previous Question Paper || Download M.Tech 2nd Sem 9D15203 Mechanical Vibrations Question Paper || JNTU Anantapur M.Tech Previous Question Paper
M.Tech II Semester Supplementary Examinations February 2018
MECHANICAL VIBRATIONS
(Machine Design)
(For students admitted in 2012, 2013, 2014, 2015 & 2016 only)
Time: 3 hours Max. Marks: 60
Answer any FIVE questions
All questions carry equal marks
*****
1 (a) Define transmissibility and derive an expression for the transmissibility ratio and the phase angle
for transmitted force.
(b) A machine of total mass 68 kg mounted on spring of stiffness k = 1100 kN/m with an assumed
damping factor of 0.2. A piston within the machine has a mass of 2 kg has a reciprocating motion
with stroke of 75 mm and speed of 3000 rev/min. Assuming the motion of piston to be SHM.
Determine: (i) Amplitude of machine.
(ii) Phase angle with respect to exciting force.
(iii) Transmissibility and force transmitted to foundation.
(iv) Phase angle of transmitted force.
2 (a) Show that the response to a unit step function, designated by g(t), is related to impulsive
response h(t) by the equation h(t) = g(t).
(b) A force F(t) us suddenly applied to a mass m which is supported by a spring with a constant
stiffness k N/m. After a short period of time T, the force is suddenly removed. During the time the
force is active, it is constant, T. Determine the response of the system if t > T. The spring and
mass are initially at rest before the force F(t) is applied.
3 (a) A vibrometer gives a reading relative displacement 0.5 mm. The natural frequency of vibration is
600 rev/min and the machine runs at 200 rev/min. Determine the magnitude of displacement,
velocity and acceleration of the vibrating machine part.
(b) Explain the working principle of seismic instrument when it measure displacement and
acceleration.
4 (a) Determine the differential equation, natural frequency and the amplitude ratio of the system
shown in figure below:
(b) Explain the working principle of dynamic vibration absorber.
Contd. in page 2
Page 1 of 2
k
M
?
m
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Code: 9D15203
M.Tech II Semester Supplementary Examinations February 2018
MECHANICAL VIBRATIONS
(Machine Design)
(For students admitted in 2012, 2013, 2014, 2015 & 2016 only)
Time: 3 hours Max. Marks: 60
Answer any FIVE questions
All questions carry equal marks
*****
1 (a) Define transmissibility and derive an expression for the transmissibility ratio and the phase angle
for transmitted force.
(b) A machine of total mass 68 kg mounted on spring of stiffness k = 1100 kN/m with an assumed
damping factor of 0.2. A piston within the machine has a mass of 2 kg has a reciprocating motion
with stroke of 75 mm and speed of 3000 rev/min. Assuming the motion of piston to be SHM.
Determine: (i) Amplitude of machine.
(ii) Phase angle with respect to exciting force.
(iii) Transmissibility and force transmitted to foundation.
(iv) Phase angle of transmitted force.
2 (a) Show that the response to a unit step function, designated by g(t), is related to impulsive
response h(t) by the equation h(t) = g(t).
(b) A force F(t) us suddenly applied to a mass m which is supported by a spring with a constant
stiffness k N/m. After a short period of time T, the force is suddenly removed. During the time the
force is active, it is constant, T. Determine the response of the system if t > T. The spring and
mass are initially at rest before the force F(t) is applied.
3 (a) A vibrometer gives a reading relative displacement 0.5 mm. The natural frequency of vibration is
600 rev/min and the machine runs at 200 rev/min. Determine the magnitude of displacement,
velocity and acceleration of the vibrating machine part.
(b) Explain the working principle of seismic instrument when it measure displacement and
acceleration.
4 (a) Determine the differential equation, natural frequency and the amplitude ratio of the system
shown in figure below:
(b) Explain the working principle of dynamic vibration absorber.
Contd. in page 2
Page 1 of 2
k
M
?
m
Code: 9D15203
5 (a) Determine the flexibility influence coefficients for stations 1, 2, 3 of the uniform cantilever beam
shown in figure below:
(b) Explain the Eigen values and Eigen vectors and orthogonal properties of Eigen vectors.
6 Determine the natural frequencies of the system shown in figure below by Holzer?s method.
7 (a) Derive suitable expression for longitudinal vibrations for a rectangular uniform cross-section bar of
length fixed at one end and free at the other end.
(b) Determine the normal functions in transverse vibration for a simply supported beam of length
and having uniform cross section.
8 (a) The rotor of a turbo super charger of mass 9 kg is keyed to the centre of a 25 mm diameter steel
shaft 400 mm long between bearing. Determine: (i) The critical speed of shaft. (ii) The amplitude
of vibration of the rotor at a speed of 3200 rpm if the eccentricity is 0.015 mm. (iii) The vibratory
force transmitted to the bearing at this speed. Assume the shaft to be simply supported.
(b) Explain the term whirling or critical speed of a shaft. Prove that the whirling speed for a rotating
shaft with damping is same as the natural frequency of the natural transverse vibration.
*****
Page 2 of 2
m
1
m
2
m
3
(1) (2) (3)
3 k
2 k
k
4 m 2 m m
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This post was last modified on 31 July 2020